Hamilton cycles in claw-heavy graphs

A graph G on n >= 3 vertices is called claw-heavy if every induced claw (K-1,K-3) of G has a pair of nonadjacent vertices such that their degree sum is at least n. In this paper we show that a claw-heavy graph G has a Hamilton cycle if we impose certain additional conditions on G involving numbers of common neighbors of some specific pair of nonadjacent vertices, or forbidden induced subgraphs. Our results extend two previous theorems of Broersma, Ryjacek and Schiermeyer [H.J. Broersma, Z. Ryjacek, I. Schiermeyer, Dirac's minimum degree condition restricted to claws, Discrete Math. 167-168 (1997) 155-166], on the existence of Hamilton cycles in 2-heavy graphs. (C) 2008 Elsevier B.V. All rights reserved.